Q: If a solution contains 1 M NaCl, what is its osmolarity, assuming complete dissociation and a dissociation factor of 1.8?

$$1 \text{ M} \times 1.8 = 1.8 \text{ OsM}$$

Q: Which equation correctly relates molarity and osmolarity for a solution of a non-dissociating solute?

$$\text{osmolarity (osmol/L)} = \text{molarity (mol/L)} \times \text{number of particles per molecule}$$

Q: A solution contains 1 M glucose and 1 M NaCl. What is the total osmolarity of the solution, assuming complete dissociation of NaCl (dissociation factor = 2)?

$$1 \text{ OsM (glucose)} + 2 \text{ OsM (NaCl)} = 3 \text{ OsM}$$

Question 1

Which of the following best describes the process of osmosis in the context of body fluid compartments?

Accepted Answer

Osmosis is the movement of water molecules from an area of low solute concentration to an area of high solute concentration across a selectively permeable membrane.

Question 2

A 58-kg Reference Woman has total body water equivalent to 50% of her body weight. What is her total body water volume in liters?

Accepted Answer

$$58 	imes 0.5 = 29$$ liters

Question 3

If a solution contains 1 M NaCl, what is its osmolarity, assuming complete dissociation and a dissociation factor of 1.8?

Accepted Answer

$$1 	ext{ M} 	imes 1.8 = 1.8 	ext{ OsM}$$

Question 4

Which of the following statements about osmolarity is correct?

Accepted Answer

Osmolarity is the number of osmotic particles per liter of solution, regardless of the type of particle.

Question 5

A selectively permeable membrane separates two compartments: A (pure water) and B (glucose solution). What will happen over time?

Accepted Answer

Water will move from A to B, diluting the glucose solution in B.

Question 6

Given that the normal osmolarity of the human body is approximately 300 mOsM, what would happen if a person is given an intravenous solution with an osmolarity of 400 mOsM?

Accepted Answer

Cells will shrink as water moves out of them.

Question 7

Which equation correctly relates molarity and osmolarity for a solution of a non-dissociating solute?

Accepted Answer

$$	ext{osmolarity (osmol/L)} = 	ext{molarity (mol/L)} 	imes 	ext{number of particles per molecule}$$

Question 8

If a 70-kg Reference Man has 60% of his body weight as water, how many liters of water does he have?

Accepted Answer

$$70 	imes 0.6 = 42$$ liters

Question 9

Which of the following best explains why infants have a higher percentage of body water than adults?

Accepted Answer

Infants have less adipose tissue and more water-rich tissues compared to adults.

Question 10

A solution contains 1 M glucose and 1 M NaCl. What is the total osmolarity of the solution, assuming complete dissociation of NaCl (dissociation factor = 2)?

Accepted Answer

$$1 	ext{ OsM (glucose)} + 2 	ext{ OsM (NaCl)} = 3 	ext{ OsM}$$

Question 11

Which of the following statements about osmotic pressure is correct?

Accepted Answer

Osmotic pressure is the force required to prevent water from moving into a solution by osmosis.

Question 12

If a cell is placed in a solution with lower osmolarity than its cytoplasm, what will happen to the cell?

Accepted Answer

The cell will swell as water enters the cell.

Question 13

Which of the following best describes the difference between molarity and osmolarity?

Accepted Answer

Molarity measures the number of moles of solute per liter of solution, while osmolarity measures the number of osmotic particles per liter of solution.

Question 14

A patient loses 2 kg of body weight due to dehydration. Approximately how many liters of water has the patient lost?

Accepted Answer

$$2$$ liters

Question 15

Which of the following is true regarding the distribution of water in the body?

Accepted Answer

About two-thirds of total body water is found in the intracellular fluid.

Question 16

If the extracellular fluid (ECF) makes up one-third of total body water, how much ECF does a 70-kg man with 60% body water have?

Accepted Answer

$$70 	imes 0.6 = 42$$ liters; $$42 \div 3 = 14$$ liters

Question 17

Which of the following best explains why osmolarity is a better measure than molarity for predicting water movement in biological systems?

Accepted Answer

Osmolarity accounts for the number of particles in solution, which determines osmotic pressure.

Question 18

A solution contains 1 M CaCl$$_2. $$Assuming complete dissociation, what is its osmolarity?

Accepted Answer

$$1 	ext{ M} 	imes 3 = 3 	ext{ OsM}$$

Question 19

Which of the following is the correct unit for osmotic pressure in physiology?

Accepted Answer

Millimeters of mercury (mm Hg)

Osmosis and Tonicity: Water Balance in the Human Body

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